Ignition System: Description and Operation
DESCRIPTIONThe ignition system controls fuel combustion by providing a spark to ignite the compressed air/fuel mixture at the correct time. To provide improved engine performance, fuel economy, and control of exhaust emissions, the control module controls distributor spark advance (timing) with the Ignition Control (IC) system.
The ignition system uses a primary and secondary sub system to accomplish timed spark distribution. The primary system consists of a low voltage trigger device which determines base timing. This signal is modified by the ignition control module and sent to the engine and/or transmission processor (control module) for base timing reference. Another signal is sent back to the ignition control module, which has been adjusted by the control module (advanced or retarded) to trigger the coil, according to the requirements of the engine.
The secondary system consists of the ignition coil which has primary (low voltage) windings and secondary (high voltage) windings. The high voltage the secondary side of the coil generates is conducted to the spark plugs by high tension plug wires.
The distributor ignition system has a distributor module with four terminals for the IC system that are connected by the control module.
To properly control ignition/combustion timing, the control module needs to know:
^ Crankshaft position.
^ Engine speed (RPM).
^ Engine load (manifold pressure or vacuum).
^ Atmospheric (barometric) pressure.
^ Engine coolant temperature.